When focussing on infinity which f-stop should I be using ???My research into this topic is confusing Some say F22 and some say wide open.

I might be missing something.Your aperture shouldn't have anything to do with your focus. Your aperture should be controlled solely to achieve a particular shutter speed (in S or Tv) or to achieve a specific depth of field.

Big f-stop number for landscapes , small f-stop number for separating subject from background (taken from a Getaway on line newsletter)

KNP is sacred.I am opposed to the modernisation of Kruger and from the depths of my soul long for the Kruger of yesteryear! 1000+km on foot in KNP incl 56 wild trails.200+ nights in the wildernessndloti-indigenous name for serval.

It really is up to you, not dependant on focussing. Obviously when you are at infinity, you most probably are shooting subjects / landscape some distance from you, so generally your AV shoul be about 8 or higher, but there's no rule as far as I know.

The only time I have really use the infinity mark on my lenses is when I am shooting landscapes and focus manually, but even then I focus most of the time on the 1/3 plane auto focus.

The only other real time I use the infinity mark is when shooting in the dark, especially lightning that is quite far away. The lens can't auto focus on a dark subject so far away, thus the infinity mark gives me a reference for me to know my shot will be in focus. I still play around with my apperture / ISO / shutter speed etc.which is obviously not related to my focussing degree.

Hi Everybody - Whenever I took scenery shots I was told to focus a third of the way up the frame - this is I was told the hyperfocal distance Is there a way of determining this point of focus more accurately and if so where do I get that for example for my 10-20mm lens?

I also heard that lenses have an optimum aperture for DOF - usually one or two stops inside the narrowest setting. Is this correct?

You can get more accurate ways to tell your hyperfocal distance and I have posted some links below that should help. After a while you will get to know your hyperfocal distances so you won't have to refer to them.

Regarding your 2nd question then I think you are referring to the maximum aperature before becoming diffraction limited (DLA). I take it you obviously using a crop sensor DSLR ? using a 10-22mm lens but it depends on the body of your camera and not the lens. It gets lower the higher the denisty sensor so for example on a Canon 350D 8MP it is f/10.4 and on a Canon 550D/600D 18MP it is f/6.8.

You don't need a very high aperture with a wide/very wide angle lens on a crop sensor body to get a large depth of field. For example if you had a focal distance of 12mm on a crop sensor canon (x1.6) even at f/8 if you focused at approx 3ft (91cm) your DoF would be from approx 2ft (60cm) to infinity.

Hope the above helps but I wouldn't get too tied up in things like CoC or DLA if your taking good shots.

Hi Massimo - I learn every day Thank you for your reply and the links We are at present in New Zealand (has been from end Nov 2010 untill end of Aug this year -) The scenery is breathtaking and the seabirds beautiful.

I have a Canon 400D and a 40D with a 100=400 L lens for the birds and a Sigma 10-20 for the sceneries. I will use the links you so kindly made available and will hopefully improve my scenery photos.